The present invention relates to an illuminating system to be used for printed articles such as books and photographs, screen displays of personal computers or other office automation equipment, portable information terminals, portable video tape recorders and the like, or reflection type liquid crystal displays used in various monitors, and the like.
In recent years, personal computers, portable information terminals, video tape recorders and the like have been becoming increasingly small-sized and portable, making it an important issue to reduce the power consumption of their image display units. On this account, many of them have been provided with reflection type liquid crystal displays used as their image display units.
The reflection type liquid crystal display device is given screen brightness by reflecting outside light such as sunlight and indoor light. However, at places of less outside light, the device could not afford enough brightness in the screen. As a result of this, there have been invented several reflection type liquid crystal displays equipped with an illuminating system which enables screen display even at places of insufficient outside light.
An example of the illuminating system to be mounted on the reflection type liquid crystal display device is shown. FIG. 16 is a schematic cross-sectional view of a conventional illuminating system. As shown in FIG. 16, the conventional illuminating system comprises a light source 1, a reflector 2, a light guide member 63 and a compensating plate 5. In order that the reflector 2 collimates the light emitted from the light source 1, the distance from the light source 1 to a side face of the light guide member 63 is elongated. The light guide member 63 has a function of propagating the light introduced from the reflector 2 by totally reflecting the light, and a function of illuminating a reflecting plate 4 by totally reflecting the light with slopes of grooves formed in its top face to change the angle of the light. The compensating plate 5 has a function of correcting any distortion that occurs when the reflected light from the reflecting plate 4 passes the light guide member 63.
However, in the conventional illuminating system, when the light that has been transmitted by the light guide member 63 to the compensating plate 5 comes incident on the light guide member 63 again after being totally reflected by the top face of the compensating plate 5, part of the light is reflected by the slopes of the grooves of the top face of the light guide member 63 so that groove lines are more visible, as an issue. Also, whereas light is collimated by a reflector to reduce the issue of these groove lines"" visibility, the collimated light is more likely to reach one side of the light guide member 63 opposite to the light source without impinging on the slopes of the grooves of the light guide member 63. This would result in a low illuminating efficiency, as another issue.
Therefore, an object of the present invention is to provide an illuminating system which makes groove lines less visible, maintains an image of reflected light successful and offers a good illuminating efficiency.
In accomplishing these and other aspects, according to a first aspect of the present invention, there is provided an illuminating system comprising:
a light source; and
a transparent plate with the light source placed beside a side face thereof,
wherein a plurality of grooves filled with a layer having a refractive index different from a refractive index of the transparent plate are arranged at specified intervals in a surface or interior of the transparent plate.
According to a second aspect of the present invention, there is provided an illuminating system according to the first aspect, wherein a top face and a bottom face of the transparent plate are generally parallel to each other.
According to a third aspect of the present invention, there is provided an illuminating system according to the first or second aspect, wherein a condition of
xcex8 less than sinxe2x88x921(n1/n)xe2x88x92sinxe2x88x921{(1/n)sin(xcex2)}
is satisfied where n is the refractive index of the transparent plate, n1 is the refractive index of a material as the layer that fills the grooves which are the slits, xcex8 is an angle formed by each of the slits and the top face of the transparent plate and xcex2 is an angle of visibility of the illuminating system.
According to a fourth aspect of the present invention, there is provided an illuminating system comprising:
a light source;
a transparent first plate with the light source placed beside a side face thereof; and
a transparent second plate placed on a top face of the first plate,
wherein a bottom face of the first plate is a plane surface and a plurality of stepwise slopes are arranged at specified intervals in the top face of the first plate;
in a bottom face of the second plate, stepwise slopes are arranged so as to be identical in configuration to the slopes of the top face of the first plate; and
the top face of the first plate and the bottom face of the second plate are placed with a specified spacing.
According to a fifth aspect of the present invention, there is provided an illuminating system according to the fourth aspect, wherein a condition of
xcex8 less than sinxe2x88x921(n2/n)xe2x88x92sinxe2x88x921{(1/n)sin(xcex2)}
is satisfied where n is the refractive index of the first plate, n2 is the refractive index of a material as the layer bonding the first plate and the second plate to each other, xcex8 is an angle of each of the slopes of the top face of the first plate and the bottom face of the second plate and xcex2 is an angle of visibility of the illuminating system.
According to a sixth aspect of the present invention, there is provided an illuminating system according to the fifth aspect, wherein a light outgoing angle of a collimator placed at an outgoing exit of the light source is within xc2x1sinxe2x88x921[nxsin{90xe2x88x92xcex8xe2x88x92sinxe2x88x921(n2/n)}].
According to a seventh aspect of the present invention, there is provided an illuminating system by overhead irradiation comprising:
a light source;
a transparent plate which is a light guide member in which a plurality of grooves are arranged in a top face of the light guide member at specified intervals in a direction parallel to a longitudinal direction of the light source, and in which a flat portion constituting a part of the top face is arranged between adjacent ones of the grooves, wherein an illumination object placed on a bottom face side of the light guide member is observed from a top face side of the light guide member.
According to an eighth aspect of the present invention, there is provided an illuminating system by overhead irradiation according to the seventh aspect, wherein each of the grooves of the light guide member is a V-shaped groove having a first slope located on one side closer to the light source and a second slope located on the other side farther from the light source, and wherein an angle xcex81 formed by the first slope and the bottom face of the light guide member falls within a range of xcex81xe2x89xa690xc2x0xe2x88x92xcex8c+2xcex83, where xcex8c is a total reflection angle of the light guide member and xcex83 is an angle formed by the flat portion and the bottom face of the light guide member.
According to a ninth aspect of the present invention, there is provided an illuminating system by overhead irradiation according to the seventh or eighth aspect, wherein each of the grooves of the light guide member is a V-shaped groove having a first slope located on one side closer to the light source and a second slope located on the other side farther from the light source, and wherein an angle xcex81 formed by the first slope and the bottom face of the light guide member satisfies a condition of:
xcex81≈45+xcex83xe2x88x92(1/2)sinxe2x88x921(1/nxsinxcex2), where n is a refractive index of the light guide member, xcex83 is an angle formed by the flat portion and the bottom face of the light guide member and xcex2 is an angle formed by a perpendicular of the bottom face of the light guide member and a direction of the observer.
According to a tenth aspect of the present invention, there is provided an illuminating system by overhead irradiation according to any one of the seventh to ninth aspects, wherein each of the grooves of the light guide member is a V-shaped groove having a first slope located on one side closer to the light source and a second slope located on the other side farther from the light source, and wherein an angle xcex82 formed by the second slope and the bottom face of the light guide member satisfies a condition of xcex82xe2x89xa6(1/2)sinxe2x88x921(1/n), where n is a refractive index of the light guide member.
According to an eleventh aspect of the present invention, there is provided an illuminating system by overhead irradiation according to any one of the seventh to tenth aspects, wherein in the light guide member, a pitch of the grooves is not more than a dot pitch of the illumination object.
According to a twelfth aspect of the present invention, there is provided an illuminating system by overhead irradiation according to any one of the seventh to eleventh aspects, wherein each of the grooves of the light guide member is a V-shaped groove having a first slope located on one side closer to the light source and a second slope located on the other side farther from the light source, and wherein in the light guide member, a length of the first slope is not more than {Lx(0.5/60)xxcfx80/180}, where L is a distance between the top face of the light guide member and an observer observing the illumination object.
According to a thirteenth aspect of the present invention, there is provided an illuminating system by overhead irradiation according to any one of the seventh to twelfth aspects, wherein a transparent prism sheet is placed on the top face of the light guide member, the prism sheet having, with respect to a cross-sectional shape, a plurality of projected portions having slopes of an angle xcex84 to the top face are arranged on the bottom face so that a flat portion generally parallel to the bottom face is interposed therebetween.
According to a fourteenth aspect of the present invention, there is provided an illuminating system by overhead irradiation according to the thirteenth aspect, wherein the length of the slope of the prism sheet is not more than {Lx(0.5/60)xxcfx80/180}, where L is the distance between the observer who observes the illumination object and the top face of the light guide member.
According to a fifteenth aspect of the present invention, there is provided an illuminating system comprising:
a light source; and
a transparent plate taking light from the light source through a side face thereof and projecting illumination light through a lower face thereof subjected to at least one of an anti-reflection treatment and a diffuse treatment,
wherein an illumination object which is disposed at a lower face side of the transparent plate is observed from an upper face side of the transparent plate.
According to a sixteenth aspect of the present invention, there is provided a reflection type liquid crystal display device which comprises:
the illuminating system according to the first aspect, the transparent plate taking light from the light source through a side face thereof and projecting illumination light through a lower face thereof subjected to at least one of an anti-reflection treatment and a diffuse treatment; and
a reflection type liquid crystal panel having a surface of at least one substrate thereof processed through at least one of the anti-reflection treatment and the diffuse treatment,
wherein the surface of the substrate of the liquid crystal panel processed through at least one of the anti-reflection treatment and the diffuse treatment is arranged to confront a lower face of the transparent plate, so that the reflection type liquid crystal panel is observed from an upper face side of the transparent plate.
According to a seventeenth aspect of the present invention, there is provided a reflection type liquid crystal display device which comprises:
the illuminating system according to the first aspect, the transparent plate taking light from the light source through a side face thereof and projecting illumination light through a lower face thereof subjected to at least one of an anti-reflection treatment and a diffuse treatment;
a reflection type liquid crystal panel having a surface of at least one substrate thereof processed through at least either an anti-reflection treatment or a diffuse treatment; and
a touch panel having a surface processed through a diffuse treatment,
wherein the surface of the substrate of the liquid crystal panel processed through at least either the anti-reflection treatment or the diffuse treatment is arranged to confront the lower face of the transparent plate and at the same time, the touch panel is disposed to confront an upper face of the transparent plate, so that the reflection type liquid crystal panel is observed from an upper face side of the transparent plate.
According to an eighteenth aspect of the present invention, there is provided a reflection type liquid crystal display device according to any one of the sixteenth to seventeenth aspects, wherein a haze value of the diffuse treatment provided to the surface of the substrate of the reflection type liquid crystal panel, the lower face of the transparent plate or the surface of the touch panel is set to be not larger than 20%.
According to a nineteenth aspect of the present invention, there is provided a reflection type liquid crystal display device according to any one of the sixteenth to eighteenth aspects, wherein a transparent material or a sheet of the material which has approximately the same refractive index as that of a material of the transparent plate and that of the substrate of the reflection type liquid crystal panel is interposed between the lower face of the transparent plate and the reflection type liquid crystal panel.
According to a 20th aspect of the present invention, there is provided a reflection type liquid crystal display device which comprises:
the illuminating system according to the first aspect, the transparent plate taking light from the light source through a side face thereof and projecting illumination light from a lower face thereof, and
a reflection type liquid crystal panel having an field angle control plate arranged on an upper face thereof, said control plate featuring a diffuse characteristic in one direction while being transparent in other directions,
wherein the face of the reflection type liquid crystal panel where the field angle control plate is arranged is set to confront the lower face of the transparent plate, and moreover an angle of the illumination light projected from the lower face of the transparent plate is almost agreed with a diffusion direction of the field angle control plate, so that the reflection type liquid crystal panel is observed from an upper face side of the transparent plate.
According to a 21st aspect of the present invention, there is provided a reflection type liquid crystal display device according to the 20th aspect, wherein an output angle of the transparent plate and the diffusion direction of the field angle control plate is 30-50xc2x0 to a normal direction of the reflection type liquid crystal panel.
According to a 22nd aspect of the present invention, there is provided an illuminating system according to the first aspect, wherein the light house is a group of point light sources in which point light sources are arranged on an almost straight line via a constant interval to radiate in nearly the same direction,
the illuminating system further comprising:
a reflector having an opening part and disposed to cover the group of point light sources; and
a diffusing plate set at the opening part of the reflector,
wherein the diffusing plate is separated from the group of point light sources so that quantity of light from a center of an illuminance distribution by the point light source on the diffusing plate is nearly equal to that between centers of illuminance distributions of the point light sources.
According to a 23rd aspect of the present invention, there is provided an illuminating system according to the 22nd aspect, wherein the reflector is L-shaped so as not to directly pass light emitted from the point light sources to the diffusing plate.
According to a 24th aspect of the present invention, there is provided an illuminating system according to the 22nd aspect, which further comprises a light guide member which outputs light entering from a side face thereof after emitted from the diffusing plate arranged at the opening part of the reflector of the linear light source, from a lower face side thereof by grooves formed in a lower face or an upper face thereof.